# Homework Help: Problem on atomic spectra of H-atoms

1. May 23, 2012

### agnibho

1. The problem statement, all variables and given/known data
Although H-atom contains one electron yet we get a number of lines in the spectrum of Hydrogen. Why??

2. May 23, 2012

### Infinitum

One transition causes only one line. But does the spectrum of lines come from only one single transition from one atom??

3. May 23, 2012

### Well_InTheory

What do you know about the energy levels that the electron can be in?

Ground state? Excited state? Are these continuous? ...

4. May 24, 2012

### agnibho

I think maybe that there are 2 atoms in one molecule of Hydrogen.....so if we calculate we get about 6.023 x 1023 x 2 atoms in total.
Maybe that's why we get a lot of lines?? You know 'cause we are using Hydrogen gas.

5. May 24, 2012

### Infinitum

Yes, that's for one mole of hydrogen gas molecules. And the spectrum is of-course measured for a hydrogen gas sample The atoms have various energy states. Some will be in the ground state, others in first excited state, second excited state and so on. Each atom emits a spectral line depending on which transition occurs, explaining the multiple lines.

Also, every single atom can also emit all these spectral lines. The only difference is, it emits them separately, requiring appropriate excitation for emission.

6. May 24, 2012

### Well_InTheory

We're just talking about the spectrum due to the atom here.

This depends on your knowledge level, but since this is a homework question, I'm guessing you have learned a little on the fact that the Hydrogen atom has discrete energy levels. Depending on where (in terms of energy level) the electron transitions to (label this n') and from (label this n), there is a unique spectral line, e.g. if it transitions to the ground state (n'=1) you get the Lyman series (for n=2,3,4...), and so on for n'=2 (Balmer); n'=3 (Paschen); etc...

http://en.wikipedia.org/wiki/Hydrogen_spectral_series

I can't tell what education level you're doing this for, but if you're up to it, Quantum Mechanics is where you'll find the deeper explanation of why the spectrum is discrete.

[Edit:] Actually, in the interest of re-enforcing questioning; if the fact that there are a lot of lines was because you have a lot of atoms as you've suggested, why would they be different lines, and not all one line?

Last edited: May 24, 2012